Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/igmp.c
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1 /* $NetBSD: igmp.c,v 1.43 2006/10/05 17:35:19 tls Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * Internet Group Management Protocol (IGMP) routines. 34 * 35 * Written by Steve Deering, Stanford, May 1988. 36 * Modified by Rosen Sharma, Stanford, Aug 1994. 37 * Modified by Bill Fenner, Xerox PARC, Feb 1995. 38 * 39 * MULTICAST Revision: 1.3 40 */ 41 42 #include <sys/cdefs.h> 43 __KERNEL_RCSID(0, "$NetBSD: igmp.c,v 1.43 2006/10/05 17:35:19 tls Exp $"); 44 45 #include "opt_mrouting.h" 46 47 #include <sys/param.h> 48 #include <sys/mbuf.h> 49 #include <sys/socket.h> 50 #include <sys/protosw.h> 51 #include <sys/systm.h> 52 53 #include <net/if.h> 54 #include <net/route.h> 55 56 #include <netinet/in.h> 57 #include <netinet/in_var.h> 58 #include <netinet/in_systm.h> 59 #include <netinet/ip.h> 60 #include <netinet/ip_var.h> 61 #include <netinet/igmp.h> 62 #include <netinet/igmp_var.h> 63 64 #include <machine/stdarg.h> 65 66 #define IP_MULTICASTOPTS 0 67 68 POOL_INIT(igmp_rti_pool, sizeof(struct router_info), 0, 0, 0, "igmppl", NULL); 69 struct igmpstat igmpstat; 70 int igmp_timers_are_running; 71 static LIST_HEAD(, router_info) rti_head = LIST_HEAD_INITIALIZER(rti_head); 72 73 void igmp_sendpkt(struct in_multi *, int); 74 static int rti_fill(struct in_multi *); 75 static struct router_info *rti_find(struct ifnet *); 76 static void rti_delete(struct ifnet *); 77 78 static int 79 rti_fill(struct in_multi *inm) 80 { 81 struct router_info *rti; 82 83 /* this function is called at splsoftnet() */ 84 LIST_FOREACH(rti, &rti_head, rti_link) { 85 if (rti->rti_ifp == inm->inm_ifp) { 86 inm->inm_rti = rti; 87 if (rti->rti_type == IGMP_v1_ROUTER) 88 return (IGMP_v1_HOST_MEMBERSHIP_REPORT); 89 else 90 return (IGMP_v2_HOST_MEMBERSHIP_REPORT); 91 } 92 } 93 94 rti = pool_get(&igmp_rti_pool, PR_NOWAIT); 95 if (rti == NULL) 96 return 0; 97 rti->rti_ifp = inm->inm_ifp; 98 rti->rti_type = IGMP_v2_ROUTER; 99 LIST_INSERT_HEAD(&rti_head, rti, rti_link); 100 inm->inm_rti = rti; 101 return (IGMP_v2_HOST_MEMBERSHIP_REPORT); 102 } 103 104 static struct router_info * 105 rti_find(struct ifnet *ifp) 106 { 107 struct router_info *rti; 108 int s = splsoftnet(); 109 110 LIST_FOREACH(rti, &rti_head, rti_link) { 111 if (rti->rti_ifp == ifp) 112 return (rti); 113 } 114 115 rti = pool_get(&igmp_rti_pool, PR_NOWAIT); 116 if (rti == NULL) { 117 splx(s); 118 return NULL; 119 } 120 rti->rti_ifp = ifp; 121 rti->rti_type = IGMP_v2_ROUTER; 122 LIST_INSERT_HEAD(&rti_head, rti, rti_link); 123 splx(s); 124 return (rti); 125 } 126 127 static void 128 rti_delete(struct ifnet *ifp) /* MUST be called at splsoftnet */ 129 { 130 struct router_info *rti; 131 132 LIST_FOREACH(rti, &rti_head, rti_link) { 133 if (rti->rti_ifp == ifp) { 134 LIST_REMOVE(rti, rti_link); 135 pool_put(&igmp_rti_pool, rti); 136 return; 137 } 138 } 139 } 140 141 void 142 igmp_input(struct mbuf *m, ...) 143 { 144 int proto; 145 int iphlen; 146 struct ifnet *ifp = m->m_pkthdr.rcvif; 147 struct ip *ip = mtod(m, struct ip *); 148 struct igmp *igmp; 149 u_int minlen; 150 struct in_multi *inm; 151 struct in_multistep step; 152 struct router_info *rti; 153 struct in_ifaddr *ia; 154 u_int timer; 155 va_list ap; 156 u_int16_t ip_len; 157 158 va_start(ap, m); 159 iphlen = va_arg(ap, int); 160 proto = va_arg(ap, int); 161 va_end(ap); 162 163 ++igmpstat.igps_rcv_total; 164 165 /* 166 * Validate lengths 167 */ 168 minlen = iphlen + IGMP_MINLEN; 169 ip_len = ntohs(ip->ip_len); 170 if (ip_len < minlen) { 171 ++igmpstat.igps_rcv_tooshort; 172 m_freem(m); 173 return; 174 } 175 if (((m->m_flags & M_EXT) && (ip->ip_src.s_addr & IN_CLASSA_NET) == 0) 176 || m->m_len < minlen) { 177 if ((m = m_pullup(m, minlen)) == 0) { 178 ++igmpstat.igps_rcv_tooshort; 179 return; 180 } 181 ip = mtod(m, struct ip *); 182 } 183 184 /* 185 * Validate checksum 186 */ 187 m->m_data += iphlen; 188 m->m_len -= iphlen; 189 igmp = mtod(m, struct igmp *); 190 /* No need to assert alignment here. */ 191 if (in_cksum(m, ip_len - iphlen)) { 192 ++igmpstat.igps_rcv_badsum; 193 m_freem(m); 194 return; 195 } 196 m->m_data -= iphlen; 197 m->m_len += iphlen; 198 199 switch (igmp->igmp_type) { 200 201 case IGMP_HOST_MEMBERSHIP_QUERY: 202 ++igmpstat.igps_rcv_queries; 203 204 if (ifp->if_flags & IFF_LOOPBACK) 205 break; 206 207 if (igmp->igmp_code == 0) { 208 rti = rti_find(ifp); 209 if (rti == NULL) 210 break; 211 rti->rti_type = IGMP_v1_ROUTER; 212 rti->rti_age = 0; 213 214 if (ip->ip_dst.s_addr != INADDR_ALLHOSTS_GROUP) { 215 ++igmpstat.igps_rcv_badqueries; 216 m_freem(m); 217 return; 218 } 219 220 /* 221 * Start the timers in all of our membership records 222 * for the interface on which the query arrived, 223 * except those that are already running and those 224 * that belong to a "local" group (224.0.0.X). 225 */ 226 IN_FIRST_MULTI(step, inm); 227 while (inm != NULL) { 228 if (inm->inm_ifp == ifp && 229 inm->inm_timer == 0 && 230 !IN_LOCAL_GROUP(inm->inm_addr.s_addr)) { 231 inm->inm_state = IGMP_DELAYING_MEMBER; 232 inm->inm_timer = IGMP_RANDOM_DELAY( 233 IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ); 234 igmp_timers_are_running = 1; 235 } 236 IN_NEXT_MULTI(step, inm); 237 } 238 } else { 239 if (!IN_MULTICAST(ip->ip_dst.s_addr)) { 240 ++igmpstat.igps_rcv_badqueries; 241 m_freem(m); 242 return; 243 } 244 245 timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE; 246 if (timer == 0) 247 timer =1; 248 249 /* 250 * Start the timers in all of our membership records 251 * for the interface on which the query arrived, 252 * except those that are already running and those 253 * that belong to a "local" group (224.0.0.X). For 254 * timers already running, check if they need to be 255 * reset. 256 */ 257 IN_FIRST_MULTI(step, inm); 258 while (inm != NULL) { 259 if (inm->inm_ifp == ifp && 260 !IN_LOCAL_GROUP(inm->inm_addr.s_addr) && 261 (ip->ip_dst.s_addr == INADDR_ALLHOSTS_GROUP || 262 in_hosteq(ip->ip_dst, inm->inm_addr))) { 263 switch (inm->inm_state) { 264 case IGMP_DELAYING_MEMBER: 265 if (inm->inm_timer <= timer) 266 break; 267 /* FALLTHROUGH */ 268 case IGMP_IDLE_MEMBER: 269 case IGMP_LAZY_MEMBER: 270 case IGMP_AWAKENING_MEMBER: 271 inm->inm_state = 272 IGMP_DELAYING_MEMBER; 273 inm->inm_timer = 274 IGMP_RANDOM_DELAY(timer); 275 igmp_timers_are_running = 1; 276 break; 277 case IGMP_SLEEPING_MEMBER: 278 inm->inm_state = 279 IGMP_AWAKENING_MEMBER; 280 break; 281 } 282 } 283 IN_NEXT_MULTI(step, inm); 284 } 285 } 286 287 break; 288 289 case IGMP_v1_HOST_MEMBERSHIP_REPORT: 290 ++igmpstat.igps_rcv_reports; 291 292 if (ifp->if_flags & IFF_LOOPBACK) 293 break; 294 295 if (!IN_MULTICAST(igmp->igmp_group.s_addr) || 296 !in_hosteq(igmp->igmp_group, ip->ip_dst)) { 297 ++igmpstat.igps_rcv_badreports; 298 m_freem(m); 299 return; 300 } 301 302 /* 303 * KLUDGE: if the IP source address of the report has an 304 * unspecified (i.e., zero) subnet number, as is allowed for 305 * a booting host, replace it with the correct subnet number 306 * so that a process-level multicast routing daemon can 307 * determine which subnet it arrived from. This is necessary 308 * to compensate for the lack of any way for a process to 309 * determine the arrival interface of an incoming packet. 310 */ 311 if ((ip->ip_src.s_addr & IN_CLASSA_NET) == 0) { 312 IFP_TO_IA(ifp, ia); /* XXX */ 313 if (ia) 314 ip->ip_src.s_addr = ia->ia_subnet; 315 } 316 317 /* 318 * If we belong to the group being reported, stop 319 * our timer for that group. 320 */ 321 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm); 322 if (inm != NULL) { 323 inm->inm_timer = 0; 324 ++igmpstat.igps_rcv_ourreports; 325 326 switch (inm->inm_state) { 327 case IGMP_IDLE_MEMBER: 328 case IGMP_LAZY_MEMBER: 329 case IGMP_AWAKENING_MEMBER: 330 case IGMP_SLEEPING_MEMBER: 331 inm->inm_state = IGMP_SLEEPING_MEMBER; 332 break; 333 case IGMP_DELAYING_MEMBER: 334 if (inm->inm_rti->rti_type == IGMP_v1_ROUTER) 335 inm->inm_state = IGMP_LAZY_MEMBER; 336 else 337 inm->inm_state = IGMP_SLEEPING_MEMBER; 338 break; 339 } 340 } 341 342 break; 343 344 case IGMP_v2_HOST_MEMBERSHIP_REPORT: 345 #ifdef MROUTING 346 /* 347 * Make sure we don't hear our own membership report. Fast 348 * leave requires knowing that we are the only member of a 349 * group. 350 */ 351 IFP_TO_IA(ifp, ia); /* XXX */ 352 if (ia && in_hosteq(ip->ip_src, ia->ia_addr.sin_addr)) 353 break; 354 #endif 355 356 ++igmpstat.igps_rcv_reports; 357 358 if (ifp->if_flags & IFF_LOOPBACK) 359 break; 360 361 if (!IN_MULTICAST(igmp->igmp_group.s_addr) || 362 !in_hosteq(igmp->igmp_group, ip->ip_dst)) { 363 ++igmpstat.igps_rcv_badreports; 364 m_freem(m); 365 return; 366 } 367 368 /* 369 * KLUDGE: if the IP source address of the report has an 370 * unspecified (i.e., zero) subnet number, as is allowed for 371 * a booting host, replace it with the correct subnet number 372 * so that a process-level multicast routing daemon can 373 * determine which subnet it arrived from. This is necessary 374 * to compensate for the lack of any way for a process to 375 * determine the arrival interface of an incoming packet. 376 */ 377 if ((ip->ip_src.s_addr & IN_CLASSA_NET) == 0) { 378 #ifndef MROUTING 379 IFP_TO_IA(ifp, ia); /* XXX */ 380 #endif 381 if (ia) 382 ip->ip_src.s_addr = ia->ia_subnet; 383 } 384 385 /* 386 * If we belong to the group being reported, stop 387 * our timer for that group. 388 */ 389 IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm); 390 if (inm != NULL) { 391 inm->inm_timer = 0; 392 ++igmpstat.igps_rcv_ourreports; 393 394 switch (inm->inm_state) { 395 case IGMP_DELAYING_MEMBER: 396 case IGMP_IDLE_MEMBER: 397 case IGMP_AWAKENING_MEMBER: 398 inm->inm_state = IGMP_LAZY_MEMBER; 399 break; 400 case IGMP_LAZY_MEMBER: 401 case IGMP_SLEEPING_MEMBER: 402 break; 403 } 404 } 405 406 break; 407 408 } 409 410 /* 411 * Pass all valid IGMP packets up to any process(es) listening 412 * on a raw IGMP socket. 413 */ 414 rip_input(m, iphlen, proto); 415 return; 416 } 417 418 int 419 igmp_joingroup(struct in_multi *inm) 420 { 421 int report_type; 422 int s = splsoftnet(); 423 424 inm->inm_state = IGMP_IDLE_MEMBER; 425 426 if (!IN_LOCAL_GROUP(inm->inm_addr.s_addr) && 427 (inm->inm_ifp->if_flags & IFF_LOOPBACK) == 0) { 428 report_type = rti_fill(inm); 429 if (report_type == 0) { 430 splx(s); 431 return ENOMEM; 432 } 433 igmp_sendpkt(inm, report_type); 434 inm->inm_state = IGMP_DELAYING_MEMBER; 435 inm->inm_timer = IGMP_RANDOM_DELAY( 436 IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ); 437 igmp_timers_are_running = 1; 438 } else 439 inm->inm_timer = 0; 440 splx(s); 441 return 0; 442 } 443 444 void 445 igmp_leavegroup(struct in_multi *inm) 446 { 447 448 switch (inm->inm_state) { 449 case IGMP_DELAYING_MEMBER: 450 case IGMP_IDLE_MEMBER: 451 if (!IN_LOCAL_GROUP(inm->inm_addr.s_addr) && 452 (inm->inm_ifp->if_flags & IFF_LOOPBACK) == 0) 453 if (inm->inm_rti->rti_type != IGMP_v1_ROUTER) 454 igmp_sendpkt(inm, IGMP_HOST_LEAVE_MESSAGE); 455 break; 456 case IGMP_LAZY_MEMBER: 457 case IGMP_AWAKENING_MEMBER: 458 case IGMP_SLEEPING_MEMBER: 459 break; 460 } 461 } 462 463 void 464 igmp_fasttimo(void) 465 { 466 struct in_multi *inm; 467 struct in_multistep step; 468 int s; 469 470 /* 471 * Quick check to see if any work needs to be done, in order 472 * to minimize the overhead of fasttimo processing. 473 */ 474 if (!igmp_timers_are_running) 475 return; 476 477 s = splsoftnet(); 478 igmp_timers_are_running = 0; 479 IN_FIRST_MULTI(step, inm); 480 while (inm != NULL) { 481 if (inm->inm_timer == 0) { 482 /* do nothing */ 483 } else if (--inm->inm_timer == 0) { 484 if (inm->inm_state == IGMP_DELAYING_MEMBER) { 485 if (inm->inm_rti->rti_type == IGMP_v1_ROUTER) 486 igmp_sendpkt(inm, 487 IGMP_v1_HOST_MEMBERSHIP_REPORT); 488 else 489 igmp_sendpkt(inm, 490 IGMP_v2_HOST_MEMBERSHIP_REPORT); 491 inm->inm_state = IGMP_IDLE_MEMBER; 492 } 493 } else { 494 igmp_timers_are_running = 1; 495 } 496 IN_NEXT_MULTI(step, inm); 497 } 498 splx(s); 499 } 500 501 void 502 igmp_slowtimo(void) 503 { 504 struct router_info *rti; 505 int s; 506 507 s = splsoftnet(); 508 LIST_FOREACH(rti, &rti_head, rti_link) { 509 if (rti->rti_type == IGMP_v1_ROUTER && 510 ++rti->rti_age >= IGMP_AGE_THRESHOLD) { 511 rti->rti_type = IGMP_v2_ROUTER; 512 } 513 } 514 splx(s); 515 } 516 517 void 518 igmp_sendpkt(struct in_multi *inm, int type) 519 { 520 struct mbuf *m; 521 struct igmp *igmp; 522 struct ip *ip; 523 struct ip_moptions imo; 524 #ifdef MROUTING 525 extern struct socket *ip_mrouter; 526 #endif /* MROUTING */ 527 528 MGETHDR(m, M_DONTWAIT, MT_HEADER); 529 if (m == NULL) 530 return; 531 /* 532 * Assume max_linkhdr + sizeof(struct ip) + IGMP_MINLEN 533 * is smaller than mbuf size returned by MGETHDR. 534 */ 535 m->m_data += max_linkhdr; 536 m->m_len = sizeof(struct ip) + IGMP_MINLEN; 537 m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN; 538 539 ip = mtod(m, struct ip *); 540 ip->ip_tos = 0; 541 ip->ip_len = htons(sizeof(struct ip) + IGMP_MINLEN); 542 ip->ip_off = htons(0); 543 ip->ip_p = IPPROTO_IGMP; 544 ip->ip_src = zeroin_addr; 545 ip->ip_dst = inm->inm_addr; 546 547 m->m_data += sizeof(struct ip); 548 m->m_len -= sizeof(struct ip); 549 igmp = mtod(m, struct igmp *); 550 igmp->igmp_type = type; 551 igmp->igmp_code = 0; 552 igmp->igmp_group = inm->inm_addr; 553 igmp->igmp_cksum = 0; 554 igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN); 555 m->m_data -= sizeof(struct ip); 556 m->m_len += sizeof(struct ip); 557 558 imo.imo_multicast_ifp = inm->inm_ifp; 559 imo.imo_multicast_ttl = 1; 560 #ifdef RSVP_ISI 561 imo.imo_multicast_vif = -1; 562 #endif 563 /* 564 * Request loopback of the report if we are acting as a multicast 565 * router, so that the process-level routing demon can hear it. 566 */ 567 #ifdef MROUTING 568 imo.imo_multicast_loop = (ip_mrouter != NULL); 569 #else 570 imo.imo_multicast_loop = 0; 571 #endif /* MROUTING */ 572 573 ip_output(m, (struct mbuf *)NULL, (struct route *)NULL, 574 IP_MULTICASTOPTS, &imo, (struct socket *)NULL); 575 576 ++igmpstat.igps_snd_reports; 577 } 578 579 void 580 igmp_purgeif(struct ifnet *ifp) /* MUST be called at splsoftnet() */ 581 { 582 rti_delete(ifp); /* manipulates pools */ 583 }
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